17. PHYSICS OF THE CIRCULATION SYSTEM (PART 2) Flashcards
1
Q
- What is Aortic Narrowing and Arterial Stenosis
(Narrowing)?
A
- they are the localised narrowing in the arterial lumen
- they are a result of atherosclerosis
ATHEROSCLEROSIS = a condition that develops when a
sticky substance (plaque) builds up
inside your arteries
2
Q
- What is Arterial Stenosis often related to?
A
- it can be genetic
- blood related
- lifestyle related
3
Q
- With early Atherosclerosis, what are the features that are specific to Aortic Stenosis?
A
- mechanical injury
4
Q
- With intermediate Atherosclerosis, what are the features that are specific to Aortic Stenosis?
A
- prominent early mineralisation
- nodule formation
5
Q
- With Late Atherosclerosis, what are the features that are specific to Aortic Stenosis?
A
- heavy calcification
- leaflet stiffening
6
Q
- With early Atherosclerosis, what are the features that are specific to both Aortic Stenosis and Athero-Sclerosis?
A
- endothelial injury
- low shear stress
- inflammation
7
Q
- With intermediate Atherosclerosis, what are the features that are specific to both Aortic Stenosis and Athero-Sclerosis?
A
- degradation of the extracellular matrix
- lipid deposition
- inflammation
8
Q
- With late Atherosclerosis, what are the features that are specific to both Aortic Stenosis and Athero-Sclerosis?
A
- calcification
- fibrosis
- inflammation
9
Q
- With early Atherosclerosis, what are the features that are specific to Athero-Sclerosis?
A
- fatty streak
10
Q
- With intermediate Atherosclerosis, what are the features that are specific to Athero-Sclerosis?
A
- foam cells
- smooth muscle cells
- proliferation
11
Q
- With late Atherosclerosis, what are the features that are specific to Athero-Sclerosis?
A
- plaque raptures
- thrombus
- FATAL
12
Q
- Which ratio is Stenosis quantified by?
A
- As / Ao
- this is called the Area Ratio
- it is expressed as a % of area occlusion
13
Q
- How is the relation between the pressure drop across the stenosis (▵P) and the flow of blood (Q) mathematically expressed?
A
STENOTIC RESISTANCE INCREASES WITH FLOW
STENOSIS:
- caused additional quadratic pressure loses
THIS IS ON TOP OF THE ALREADY EXISTING:
- linear and proportional pressure loses
BOTH THE FLOW AND THE AREA APPEAR AS:
- quadratic terms
- this is an important aspect of the
hemodynamics of a narrowing
14
Q
- What does the highlighted term represent?
A
- this represents the viscous losses
- these happen during Stenosis
15
Q
- What does the highlighted term represent?
A
- this represents the losses due to Turbulence
NB: Kt is an empirical coefficient
: it is equal to 1.5